BOSTON - Dozens of people, many with debilitating illnesses, asked Massachusetts health officials today to allow doctors to decide what conditions should be treated with medical marijuana.

The Department of Public Health also heard from substance-abuse groups, youth counselors and police, who urged them to draft strict regulations as the state prepares to begin offering medical marijuana to people with cancer, Parkinson's disease, AIDS and other serious health conditions.

The broad range of testimony came during the second of three "listening sessions" state health officials are holding this month as they work on regulations for the medical marijuana industry.

Voters approved the legalization of medical marijuana through a ballot question in November. Now, the department is charged with coming up with regulations on what medical conditions will be eligible, how marijuana dispensaries will be operated, what constitutes a 60-day supply of marijuana, how marijuana may be used in food products for medical purposes, who can receive a hardship registration so they can grow their own, and how dispensaries will be monitored.

Many of those who testified said they were concerned that certain ailments may not be deemed eligible for medical marijuana and urged health officials to leave that decision to doctors and their patients.

Scott Murphy, an Iraq War Army veteran who said he suffers from chronic pain, broke down in tears as he urged department officials to allow the use of medical marijuana for post-traumatic stress disorder.

"As you might be aware, we are losing one soldier a day to suicide," he said. "If medical marijuana can help one person with PTSD, I would hope you would consider that."

Murphy, 30, of Auburndale, later said in an interview that a close friend who served with him suffered from PTSD and committed suicide last year.

Murphy said he gets his medical treatment through the U.S. Veterans Affairs hospital in Boston, and he is worried his doctor there may not be able to write him a prescription for marijuana, which is still illegal under federal law.

Eric McCoy, of Boston, said he was diagnosed with multiple sclerosis 20 years ago and has used marijuana on almost a daily basis for the last 17 years. McCoy, who uses a wheelchair, said marijuana eases his muscle spasms and has helped him to be able to live without any assistance.

"It's been a saving grace for me," he said.

McCoy urged the department to allow people with multiple sclerosis to get hardship exceptions, which would allow them to grow marijuana themselves rather than requiring people with limited mobility to go to a dispensary.

"Without that, the medical marijuana, the medicine, will not be available to folks who are like me," he said.

Others who testified said they were concerned that the approval of medical marijuana, combined with the state's decriminalization of small amounts of marijuana, will make young people believe smoking marijuana is acceptable.

"What we've seen since the decriminalization in 2008 is that the perception of harm and risk of marijuana has gone way down, for both youth and their parents," said Jason Verhoosky, youth program director for Danvers CARES, a coalition that tries to prevent substance abuse.

"What we're really trying to do is educate people - it's still a drug and it still causes harm," he said.

John Carmichael Jr., deputy police chief in Walpole, urged health officials to make sure the 60-day supply of marijuana allowed under the law is "kept reasonable." He also said identification cards for people who are entitled to get medical marijuana should have photos and other security features so no one else can use them. He said medical marijuana prescriptions need to be monitored carefully to stem abuse.

"It would be naive to think there is not going to be diversion," he said.

About 100 people turned out for the hearing.

The Department of Public Health was expected to draft the regulations by May 1. When asked if that deadline would be met, interim Commissioner Dr. Lauren Smith said the department is doing its "utmost to get this done as close to May as possible."

"We have to balance the needs - the very real needs - of the patients who are seeking relief with the needs and our responsibility to protect the overall well-being of the commonwealth," she said.